Forces loyal to Libyan leader Moamar Gaddafi have clashed with rebels who have risen up against his rule on the outskirts of the oil port of Ras Lanuf, members of the rebel force say.
The armed rebels are calling for foreign air strikes to set up a no-fly zone after three days of attacks by Mr Gaddafi's warplanes.
"Yes there have been some clashes. There have been rockets and missiles from us targeting a military base which is there to protect Ras Lanuf oil terminal," said Adel Yahya, an armed rebel.
"Clashes have started. We're outside Ras Lanuf, about 10 km to 15 km away. Right now it's heavy weapons fire. Infantry will be coming later," said Bashir Warshafani, an armed volunteer member of the rebel force making his way to the front.
Eastern-based rebels say they are open to talks only on Mr Gaddafi's exile or resignation following attacks on civilians that have provoked international condemnation, a raft of arms and economic sanctions and a war crimes probe.